The axis of Uller is in the same plane as the orbit, so that at a certain time of the year the north pole is pointed directly at the sun, while at the opposite end of the orbit it points directly away. The result is highly exaggerated seasons. At the poles the temperature runs from 120°C to a low of-80°C. At the equator it remains not far from 10°C all year round. Strong winds blow during the summer and winter, from the hot to the cold pole; few winds during the spring and fall. The appearance of the poles varies during the year from baked deserts to glaciers covered with solid CO_{2}. Free water exists in the equatorial regions all year round. 2. SOLAR MOVEMENT AS SEEN FROM ULLER As seen from the north pole--no sun is visible on Jan. 1. On April 1, it bisects the horizon all day, swinging completely around. April 1 to July 1, it continues swinging around, gradually rising in the sky, the spiral converging to its center at the zenith, which it reaches July 1. From July 1 to October 1 the spiral starts again, spreading out from the center until on October 1 it bisects the horizon again. On October 1 night arrives to stay until April 1. At the equator, the sun is visible bisecting the southern horizon for all 26 hours of the day on January 1. From January 1 to April 1, the sun starts to dip below the horizon at night, to rise higher above it during the day. During all this time it rises and sets at the same hours, but rises in the southeast and sets in the southwest. At noon it is higher each day in the southern sky until April 1, when it rises due east, passes through the zenith and sets due west. From April 1 to July 1, its noon position drops down to the north, until on July 1, it is visible all day, bisected by the northern horizon. 3. CHEMISTRY AND GEOLOGY OF ULLER Calcium and chlorine are rarer than on earth, sodium is somewhat commoner. As a result of the shortage of calcium there is a higher ration of silicates to carbonates than exists on earth. The water is slightly alkaline and resembles a very dilute solution of sodium silicate (water glass). It would have a pH of 8.5 and tastes slightly soapy. Also, when it dries out it leaves a sticky, and then a glassy, crackly film. Rocks look fairly earthlike, but the absence or scarcity of anything like limestone is noticeable. Practically all the sedimentary rocks are of the sandstone type. All rivers are seasonal, running from the polar regions to the central seas in the spring only, or until the polar cap is completely dried out. 4. ANIMAL LIFE